In the individual event he was defeated in the third round. Gu finished the 2013-2014 season ranked #1 in the world, claiming of Korea"s first Fencing World Cup title. He maintained his world #1 rank to the end of the 2014-2015 season to claim his second World Cup title.
At the 2012 Summer Olympics, he competed as part of the South Korean team in the Men"s team sabre, where he won a gold medal. At the 2011 World Fencing Championships, he won the bronze medal, losing to Aldo Montano in the semifinal. At the 2014 World Fencing Championships he won silver in the individual event, losing to Nikolay Kovalev in the final. He also won silver in the team event, along with Kim Jung-hwan, Won Woo-Young and Oh Eun-seok. In the 2014-2015 Fencing World Cup he won gold at the Coupe de Monde in Budapest, the Sabre de Wolodyjowski in Warsaw and the Villa de Madrid in Madrid, before finishing 5th at the 2015 World Fencing Championships in Moscow. Gu is also the 2010, 2012 and 2014 Asian Champion, as well as the 2010 and 2014 Asian Games champion.
